With over 300,000 lower limb amputees in America, lower limb prostheses are a very important intervention to keep this population active and otherwise healthy. With nearly half of this population choosing not to use a prosthesis to replace their lost limb, there is a strong market need for better foot prostheses. Using novel technologies, the proposed prosthesis will duplicate the subtle motions and coordinations of the human foot. These motions will provide the amputees with improved gait mechanics. This improvement in gait will be seen in an oxygen consumption study, showing that users of this new prosthesis were able to ambulate with a lower energy cost per meter traveled, when walking at the same speed. Phase I first proposes to complete the designs described herein. These designs will then be subjected to rigorous bench testing, establishing that the prosthesis has more accurately modeled the biomechanics of the human foot. Bench testing will continue with fatigue testing, to ensure that the human subjects will able to safely use the novel prosthesis for a two week "break-in" period. Upon completion of this break-in period, the human subjects will participate in the oxygen consumption study mentioned above. The same technology explored in the design of this prosthesis can be applied to replace or augment every joint in the body, paving the way for broad advances in prosthetic and orthotic technology. These advances can then be applied to the military and transportation sectors.